JP2887776B2 - Liquid crystal display - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a liquid crystal display device,
The present invention relates to a field-effect liquid crystal display device having particularly excellent time-division driving characteristics and capable of displaying monochrome and multicolor images.

[0002]

2. Description of the Related Art As one type of liquid crystal display device, a twisted nematic type (TN) is a 90-degree twisted helical structure formed by a nematic liquid crystal having a positive dielectric anisotropy between two electrode substrates. And a polarizing plate is disposed outside the two electrode substrates such that the polarization axis (or absorption axis) thereof is orthogonal or parallel to the liquid crystal molecules adjacent to the electrode substrate (Japanese Patent Publication No. 51 (1988)). -136
No. 66).

[0003] Such a liquid crystal display element having a twist angle (α) of 90 degrees has problems in the steepness (γ) of the change in the transmittance of the liquid crystal layer with respect to the voltage applied to the liquid crystal layer and the viewing angle characteristics. ,
The number of time divisions (corresponding to the number of scanning electrodes) was 64, which was a practical limit. However, in order to cope with recent demands for improving image quality and increasing the amount of display information for liquid crystal display devices, a super twisted nematic (STN) having a twist angle α of liquid crystal molecules larger than 180 degrees has been proposed, and the STN has a birefringence. It is important to improve the time-sharing drive characteristics by using the effect to increase the number of time-sharing.
Letter 45, No. 10, 1021 1984 (Applied Physics Lette
r, TJScheffer, J.Nehring: "A new, highly multiplexab
le liquidcrystal display "), and a super twisted birefringence effect (SBE) liquid crystal display device has been proposed.

A liquid crystal display device of this type includes a liquid crystal display panel including an upper frame having a display window and a liquid crystal plate on which a drive circuit board is integrated, a light guide assembly including a light diffusion plate and a light guide plate, and At least an intermediate frame on which a linear backlight source is mounted on one side, and at least a lower frame,
These are laminated in the above order, and the upper frame and the lower frame are connected and fixed.

[0005] The upper frame and the lower frame are made of a thin iron plate, and the whole is tightly laminated by interposing an appropriate spacer or an adhesive tape or the like as necessary between the above-mentioned components to form an integral unit. It is held fixed so that it can be handled.

[0006]

In the above-mentioned conventional liquid crystal display device, since the upper frame and the lower frame are formed of thin iron plates, the thickness and weight of the entire liquid crystal display device are increased, and the entire liquid crystal display device is increased. There is a limit in reducing the thickness and weight of the liquid crystal display device while maintaining the rigidity, and there is a problem that heat generated by the backlight light source is locally transmitted to the liquid crystal display panel to cause display unevenness.

An object of the present invention is to solve the above-mentioned problems of the prior art, maintain the rigidity of the entire liquid crystal display device, make it thinner and lighter, and suppress display unevenness due to heat generation of a backlight light source. A display device is provided.

[0008]

In order to achieve the above object, a liquid crystal display device 63 according to the present invention is provided with a metallic upper frame 1 having a display window 3 and disposed below the upper frame.
A liquid crystal display panel 62 comprising a liquid crystal display element and a driving circuit board 35 for the liquid crystal display element integrally formed around the liquid crystal display element; and a light diffusion plate disposed below the liquid crystal display panel. Light guide assembly 37 formed by laminating a light guide plate
And the light guide assembly 37 is disposed below the light guide assembly.
And an intermediate frame 42 having a space for mounting the linear backlight light source 36 on at least one side, and disposed below the intermediate frame and connected to the upper frame to form the upper frame. Metallic lower frame 2 for fixing each of the members (62, 37, 42) disposed therebetween, having a predetermined shape along the longitudinal direction of the backlight light source immediately below the backlight light source. And a lower frame having cutouts 57 and 58.

The area (S ₁ + S ₂ + S ₃ ) of the lower frame formed immediately below the backlight source 36 is 10% to 5% of the area (L) occupied by the backlight source.
It is preferable to provide the cutout portions 57 and 58 so as to be 0%.
Area of the lower frame (S ₁ + S ₂ +
The feature of the present invention is that the cutout portions 57 and 58 are provided so that S ₃ ) is approximately 30% of the area (L) occupied by the backlight light source.

The lower frame 2 further includes cutouts 53 provided at positions corresponding to both ends of the backlight light source.
The feature of the present invention is that the area 54 is provided. In this case, the area (S ₁ + S ₂ + S ₃ ) of the lower frame formed immediately below the backlight light source 36 is the area occupied by the backlight light source ( L), the cutout portions 57 and 58 and the cutout portions 53 and 54 are provided so as to be 10% to 50% with respect to L. As a more preferred embodiment, the lower portion formed immediately below the backlight light source 36 is provided. Frame area (S
₁ + S ₂ + S ₃ ) is approximately 30% of the area (L) occupied by the backlight light source,
It is a feature of the present invention to provide the notch 58 and the notches 53 and 54.

The lower frame 2 is further provided at a position symmetrical to a line passing through the center of the backlight light source 36 and orthogonal to the longitudinal direction of the backlight light source 36 over a region corresponding to the liquid crystal display panel 62. It is also a feature of the present invention to provide cutouts 55 and 56 having predetermined shapes. In this case, the area of the lower frame 2 formed below the liquid crystal display panel 62 is reduced by the area of the liquid crystal display panel. The cutouts 55 and 56 may be provided so as to be 10% to 50% of the occupied area, and more preferably, the area (L) of the lower frame formed below the liquid crystal display panel is: The feature of the present invention is that the cutouts 55 and 56 are provided so as to be approximately 30% of the area (S ₁ + S ₂ + S ₃ ) occupied by the liquid crystal display panel.

The above-mentioned features are appropriately combined, or
The invention constituted by adopting it alone is also a feature of the present invention, and the feature of the present invention is that the upper frame 1 is formed of a stainless steel sheet and the lower frame 2 is formed of an aluminum sheet.

[0013]

As described above, the cut-out portions 57, 58 or the cut-out portions 53, 54 provided in the lower frame 2 prevent the "leakage current" from being reduced and the luminance from being reduced due to the heat radiation effect.
In addition, the temperature distribution of the liquid crystal display panel 62 is made uniform, and the cutouts 55 and 56 can make the temperature distribution of the liquid crystal display panel 62 uniform and improve the weight of the liquid crystal display device by improving the heat radiation effect. . As described above, the cutout portions 57 and 58 or the cutout portions 53 and 54 are
The area (S ₁ + S ₂ + S ₃ ) of the lower frame formed immediately below the backlight light source 36 is 10% to 50% (particularly preferably about 30%) with respect to the area (L) occupied by the backlight light source. And the cutout 5
The area of the lower frame 2 formed below the liquid crystal display panel 62 is 10% to 50% of the area occupied by the liquid crystal display panel (particularly preferably about 30%).
%), A more favorable effect can be obtained in terms of the intensity of the frame, the luminance of the backlight light source, and the like. Further, by forming the upper frame 1 from a thin stainless steel plate and configuring the lower frame 2 from an aluminum thin plate, the rigidity is increased, the thickness of the intermediate frame 42 is reduced, and the weight of the liquid crystal display device can be reduced.

[0014]

Embodiments of the present invention will be described below in detail with reference to the drawings.

FIG. 1 is an exploded perspective view for explaining the structure of a liquid crystal display device 63 according to the present invention.
Is a liquid crystal display window, 62 is a liquid crystal display panel, 35 is a drive circuit board, 13 is a spacer, 37 is a light guide assembly composed of a light diffusion plate, a light guide plate and a reflection plate, and 42 is a linear backlight source mounted. An intermediate frame, 36 is a linear backlight light source (lamp) composed of a cold cathode tube, 17 is a lamp cover, and 2 is a lower frame.

Reference numeral 18 denotes a cut-and-raised piece that contacts the ground pad 24 formed on the drive circuit board 35;
Are nails fixed to a nail receiver 25 formed on the lower frame;
Is an adhesive tape for fixing the upper frame 1 to the liquid crystal display panel, 55 and 56 are cutouts provided at positions symmetrical to a line orthogonal to the center of the backlight, and 57 and 58 are provided in the longitudinal direction of the backlight light source 36. Cutout, 53,5
Reference numeral 4 denotes a notch provided at a lower part of both ends of the backlight light source 36. The upper frame is, for example, a steel plate having a thickness of 0.8 mm, and the lower frame is a steel plate or an equivalent thickness of, for example, 0.1 mm.
It is composed of 5 mm thick aluminum.

In the figure, the liquid crystal display panel is sandwiched and fixed between the upper frame 1 and the lower frame 2 in the order shown in the figure. A linear light source (backlight light source) 36 composed of a cold cathode tube is installed at one end of the intermediate frame 42, the lamp cover 17 blocks direct light toward the liquid crystal display panel 62, and the emitted light is diffused by a light diffusion plate. And a light guide plate 37.

The spacer 13 is interposed between the light guide assembly 37 provided in the recess formed in the intermediate frame 42 and the liquid crystal display panel 62 to define a display area.

The upper frame 1 is formed of a stainless steel sheet, and the lower frame 2 is formed of an aluminum sheet. At least a pair of cutouts 55 and 56 are provided at positions symmetrical to a line orthogonal to the center of the backlight light source over at least the area of the liquid crystal display panel 62 in a direction orthogonal to the backlight light source 36 of the lower frame 2. At least two cutout portions 57, 58 provided in the longitudinal direction of the backlight light source 36 directly below the backlight light source 36, and cutouts 53, 54 provided in lower portions of both ends of the backlight light source 36. Are formed.

As described above, according to the present embodiment, the upper frame 1 is made of a stainless steel thin plate and the lower frame 2 is made of an aluminum thin plate, thereby achieving a reduction in thickness and weight without reducing the rigidity of the liquid crystal display device. At the same time, cutouts 55 and 5 provided at positions symmetrical to a line orthogonal to the center of the backlight light source over at least the area of the liquid crystal display panel 62 in a direction orthogonal to the backlight light source 36.
6, cutout portions 57 and 58 provided in the longitudinal direction of the backlight light source 36 directly below the backlight light source 36, and a notch 5 provided in a lower part of both ends of the backlight light source 36.
3, 54, the heat radiation effect is improved, a uniform temperature distribution is formed on the entire surface of the liquid crystal display panel 62, and the occurrence of display unevenness is prevented.

Further, since the backlight light source 36 is driven at a high frequency, the lower frame 2 and the backlight light source 36
A current flows from the backlight light source 36 to the lower frame 2 through the stray capacitance between the lower frame 2. This current is called “leakage current”, and the amount of current that contributes to lighting of the backlight light source 36 decreases by the amount of “leakage current”.
The brightness will be reduced. Also, the backlight light source 3
6 generates heat by being lit for a long time, and the temperature in the vicinity of the backlight light source 36 rises with respect to the outside air. Therefore, if no measures are taken, the heat in the vicinity of the backlight light source 36 becomes And the temperature distribution of the liquid crystal display panel cannot be made uniform. Therefore, in the above embodiment, the cutout portions 57 and 58 are provided to prevent a decrease in luminance due to “leakage current” and to make the temperature distribution of the liquid crystal display panel uniform, thereby preventing display unevenness.
Further, the cutout portions 57 and 58 can prevent a decrease in luminance due to thermal diffusion of the backlight light source.

Further, both ends of the backlight light source 36
In particular, it is a portion that causes a decrease in luminance due to a decrease in temperature, and it is necessary to increase the temperature within a range where uniformity of the temperature distribution of the liquid crystal display panel can be maintained. Therefore, notches 53 and 54 are provided so as to make the temperature distribution of the liquid crystal display panel uniform and prevent a decrease in luminance. Functionally, the same effects as those of the cutout portions 57 and 58 are obtained.

The cutouts 55 and 56 provided at positions symmetrical with respect to a line orthogonal to the center of the backlight source over the area of the liquid crystal display panel 62 reduce the weight of the lower frame 2 and reduce the weight of the liquid crystal display panel. Temperature distribution can be made uniform. Further, the above-mentioned cutout portions 57 and 58, notches 53 and 54, cutout portions 55 and 56
The area ratio in the lower frame 2 will be described.

FIG. 2 is a plan view of the lower frame 2. At the positions of the cutouts 57 and 58 and the cutouts 53 and 54, the backlight light source 36 is arranged as shown in the drawing. Although not shown, the backlight light source 36 includes a power supply cable, and the cable is arranged substantially parallel to the backlight light source 36. Here, assuming that the length of the portion of the backlight light source 36 and the power supply cable is L, the portions where the lower frame 2 except for the cutout portions 57 and 58 and the cutouts 53 and 54 exist are S ₁ and S _2. , S ₃
Becomes In the present invention, the ratio (L) in which the fluorescent tube and the power supply cable of the backlight light source 36 are arranged is:
It is characterized in that the ratio (S ₁ + S ₂ + S ₃ ) of the portion where the lower frame 2 located immediately below exists is 10% to 50% (particularly preferably about 30%). If expressed by the equation, 0.1 ≦ (S ₁ + S ₂ + S ₃ ) /L≦0.5.

By forming the cutout portions 57 and 58 or the cutouts 53 and 54 at the above-described ratio, a decrease in luminance due to "leakage current" and heat diffusion is prevented, and the temperature distribution of the liquid crystal display panel is made uniform. Prevention of display unevenness due to
Can be more effectively achieved.

Similarly, the cutouts 55 and 56 are also formed from the viewpoint of making the temperature distribution of the liquid crystal display panel uniform.
An important point is the area ratio to the light guide assembly 37. That is, the ratio of the portion where the lower frame 2 exists corresponding to the portion where the light guide assembly 37 is arranged is set to 10% to 50%.
% (Particularly preferably about 30%)
It is possible to more effectively prevent the occurrence of display unevenness due to the uniform temperature distribution of the liquid crystal display panel. In this case, the width of the liquid crystal display element of the liquid crystal display panel 62 or the width of the light guide assembly 37 is L, and the portion where the lower frame 2 corresponding to the portion where the light guide assembly 37 is disposed is S. ₄ , S ₅ S ₆ , 0.1 ≦ (S ₄ + S ₅ + S
₆ ) /L≦0.5.

A specific example in which the above configuration is applied to a super twisted nematic (STN) type liquid crystal display device will be described below. In the following drawings, those having the same functions are denoted by the same reference numerals, and their repeated description will be omitted.

[Specific Example 1] FIG. 3 shows a liquid crystal display panel 62 according to the present invention viewed from above, in which liquid crystal molecules are arranged (eg, rubbing direction), the liquid crystal molecules are twisted, and the polarizing axis (or absorption axis) of the polarizing plate. 4) shows the direction of the optical axis of the member providing the birefringence effect, and FIG. 4 shows a perspective view of the main part of the liquid crystal display panel 62 according to the present invention.

The twist direction 10 and the twist angle θ of the liquid crystal molecules
The rubbing direction 6 of the alignment film 21 on the upper electrode substrate 11 and the rubbing direction 7 of the alignment film 22 on the lower electrode substrate 12 and the nematic liquid crystal layer 50 sandwiched between the upper electrode substrate 11 and the lower electrode substrate 12 It is defined by the type and amount of the optical rotation substance added.

In FIG. 4, in order to align the liquid crystal molecules in a twisted spiral structure between the two upper and lower electrode substrates 11 and 12 sandwiching the liquid crystal layer 50, the upper and lower electrode substrates 1 and 12 are required.
The surfaces of the alignment films 21 and 22 made of an organic polymer resin made of, for example, polyimide, in contact with the liquid crystal on
For example, a method of rubbing in one direction with a cloth or the like, a so-called rubbing method is employed. The rubbing direction at this time, that is, the rubbing direction, that is, the rubbing direction 6 in the upper electrode substrate 11 and the rubbing direction 7 in the lower electrode substrate 12 is the alignment direction of the liquid crystal molecules.

On the two sheets thus oriented,
The lower electrode substrates 11 and 12 are moved in the respective rubbing directions 6,7.
Are opposed to each other with a gap d1 so as to intersect at approximately 180 degrees to 360 degrees with each other.
Are bonded by a frame-shaped sealing material 52 having a cutout portion 51 for injecting liquid crystal, and a nematic liquid crystal having a positive dielectric anisotropy and having a predetermined amount of an optical rotation substance added thereto is filled in a gap therebetween, thereby obtaining liquid crystal molecules. Is the twist angle θ in the figure between the electrode substrates
Has a helical structure. Here, 31 and 32 are upper and lower electrodes, respectively.

A member (hereinafter, referred to as a birefringent member) 40 for providing a birefringence effect is disposed above the upper electrode substrate 11 of the liquid crystal cell 60 thus configured. Upper and lower polarizers 15 and 16 are provided with the cell 60 interposed therebetween. The twist angle θ of the liquid crystal molecules in the liquid crystal layer 50 is preferably from 200 degrees to 300 degrees. However, it is possible to avoid a phenomenon in which the lighting state near the threshold of the transmittance-applied voltage curve becomes an alignment that scatters light. From the practical viewpoint of maintaining characteristics, the range of 230 to 270 degrees is more preferable.

This condition basically acts to make the response of the liquid crystal molecules to a voltage more sensitive and to realize excellent time division characteristics. In order to obtain excellent display quality, the product [Delta] n ₁ · d ₁ of the refractive index anisotropy [Delta] n ₁ and a thickness d ₁ of the liquid crystal layer 50 is preferably from the 0.5 [mu] m 1.0 micron
m, more preferably in the range of 0.6 μm to 0.9 μm.

The birefringent member 40 functions to modulate the polarization state of the light transmitted through the liquid crystal cell 60, and converts the liquid crystal cell 60, which could only be colored by itself, to monochrome display. For this purpose, the product [Delta] n ₂ · d ₂ of the refractive index anisotropy [Delta] n ₂ and the thickness d ₂ of the birefringent member 40 is extremely important, 0.8 micron preferably from 0.4μm
m, more preferably in the range of 0.5 μm to 0.7 μm.

Further, the liquid crystal display panel 62 according to the present invention
Uses elliptically polarized light due to birefringence.
In the case where a uniaxial transparent birefringent plate is used as the birefringent member 40, the relationship between the optic axes and the liquid crystal alignment directions 6 and 7 of the electrode substrates 11 and 12 of the liquid crystal cell 60 is extremely important. It is.

Here, the operation and effect of the above relationship will be described with reference to FIG. This figure shows the relationship between the axis of the polarizing plate, the optical axis of the uniaxial transparent birefringent member, and the liquid crystal array direction of the electrode substrate of the liquid crystal cell when the liquid crystal display device having the configuration of FIG. 4 is viewed from above. is there.

In FIG. 3, 5 is the optical axis of the uniaxial transparent birefringent member 40, 6 is the liquid crystal alignment direction of the birefringent member 40 and the upper electrode substrate 11 adjacent thereto, and 7 is the liquid crystal alignment of the lower electrode substrate 12. The direction 8 is an absorption axis or a polarization axis of the upper polarizing plate 15, the angle α is the angle between the liquid crystal alignment direction 6 of the upper electrode substrate 11 and the optical axis 5 of the uniaxial birefringent member 40, and the angle β is the upper direction. The angle and angle γ between the absorption axis or polarization axis 8 of the polarizing plate 15 and the optical axis 5 of the uniaxial transparent birefringent member 40 are determined by the absorption axis or polarization axis 9 of the lower polarizing plate 16 and the lower electrode substrate 1.
2 is an angle formed with the liquid crystal alignment direction 7.

Here, how to measure the angles α, β, and γ is defined. In FIG. 8, an example will be described in which the intersection angle between the optical axis 5 of the birefringent member 40 and the liquid crystal alignment direction 6 of the upper electrode substrate 11 is used.

The intersection angle between the optical axis 5 and the liquid crystal alignment direction 6 is shown in FIG.
Can be represented by φ ₁ and φ ₂ as shown in
Here, the smaller angle of φ ₁ and φ ₂ is adopted.
That is, since φ ₁ <φ ₂ in FIG. 8A, φ ₁ is the intersection angle between the optical axis 5 and the liquid crystal alignment direction 6, and φ ₁ > φ ₂ in FIG. 8B. Therefore, φ ₂ is the intersection angle between the optical axis 5 and the liquid crystal alignment direction 6. Of course φ ₁ = φ
_In the case of ₂ , either may be adopted.

In this type of liquid crystal display device, the angles α, β, and γ are extremely important. Is preferably 5
From 0 degrees to 90 degrees, more preferably from 70 degrees to 90 degrees,
Is preferably between 20 and 70 degrees, more preferably between 30 and 60 degrees, and angle γ is preferably between 0 and 70 degrees.
Degrees, more preferably from 0 to 50 degrees.

If the twist angle θ of the liquid crystal layer 50 of the liquid crystal cell 60 is in the range of 180 ° to 360 °, the angle α can be obtained regardless of whether the twist direction 10 is the clockwise direction or the counterclockwise direction. , Β, and γ may be within the above ranges.

In FIG. 4, the birefringent member 40 is disposed between the upper polarizing plate 15 and the upper electrode substrate 11, but instead is disposed between the lower electrode substrate 12 and the lower polarizing plate 16. May be provided. In this case, the entire configuration of FIG. 4 is inverted.

[Specific Example 2] The basic structure is the same as that shown in FIGS. In FIG. 5, the twist angle θ of the liquid crystal molecules is 240 degrees, and the uniaxial transparent birefringent member 4
As 0, a liquid crystal cell having a parallel orientation (homogeneous orientation), that is, a twist angle of 0 degree was used.

Here, the ratio d / p between the thickness d (μm) of the liquid crystal layer and the helical pitch p (μm) of the liquid crystal material to which the optical rotatory substance was added was about 0.53. The alignment films 21 and 22 were formed of a polyimide resin film, which was subjected to a rubbing treatment. The tilt angle (pretilt angle) at which the alignment film subjected to the rubbing treatment causes the liquid crystal molecules in contact with the alignment film to be tilt-aligned with respect to the substrate surface is about 4 degrees. Δn ₂ · d ₂ of the uniaxial transparent birefringent member 40 is about 0.6 μm.
On the other hand, Δn ₁ · d ₁ of the liquid crystal layer 50 having a structure in which the liquid crystal molecules are twisted by 240 degrees is about 0.8 μm.

At this time, by setting the angle α to about 90 degrees, the angle β to about 30 degrees, and the angle γ to about 30 degrees, the voltage applied to the liquid crystal layer 50 via the upper and lower electrodes 31 and 32 is reduced. When the voltage is equal to or less than the threshold, light opaque, that is, black, is obtained. When the axis of the lower polarizing plate 16 is rotated from 50 degrees to 90 degrees from the above position, the white color is applied when the voltage applied to the liquid crystal layer 50 is equal to or less than the threshold, and the black color is applied when the voltage is equal to or more than the threshold. Black and white display was realized.

FIG. 6 shows a change in contrast during time-division driving at 1/200 duty when the angle α is changed in the configuration of FIG. When the angle α is around 90 degrees, the contrast is extremely high, but the contrast decreases as the angle α deviates from this angle. In addition, when the angle α is small, the lighted portion and the non-lighted portion are both bluish, and when the angle α is large, the non-lighted portion is purple and the lighted portion is yellow. The results are almost the same for the angles β and γ. However, in the case of the angle γ, when the image is rotated from 50 degrees to nearly 90 degrees as described above, the reverse black and white display is obtained.

"Specific Example 3" The basic structure is the same as that of "Specific Example 2".
Is the same as However, the twist angle of the liquid crystal molecules of the liquid crystal layer 50 is 260 degrees, and Δn ₁ · d ₁ is about 0.65 μm to 0.75 μm.
The difference is that it is 5 μm. Δn ₂ · d ₂ of the parallel alignment liquid crystal layer used as the uniaxial transparent birefringent member 40 is about 0.58 μm, which is the same as in “Specific Example 2”.

At this time, by setting the angle α to about 100 degrees, the angle β to about 35 degrees, and the angle γ to about 15 degrees, the same monochrome display as that of the “specific example 1” was realized. Also, as in the case of "Specific Example 2", by rotating the position of the axis of the lower polarizing plate by 50 to 90 degrees from the above value, it is possible to perform inverted black and white display. The inclination with respect to the deviation of the angles α, β, γ is almost the same as in “Specific Example 2”.

In each of the above embodiments, the uniaxial transparent birefringent member 40 is a parallel alignment liquid crystal cell having no twist of liquid crystal molecules, but rather a liquid crystal layer having twisted liquid crystal molecules of about 20 to 60 degrees. When used, the color change due to the angle is small. This twisted liquid crystal layer corresponds to the liquid crystal layer 5 described above.
Similarly to the case of 0, the liquid crystal is formed by sandwiching a liquid crystal between the pair of transparent substrates which have been subjected to the alignment processing so that the alignment processing directions intersect at a predetermined twist angle. In this case, the direction of the bisecting angle between the two alignment processing directions sandwiching the twisted structure of the liquid crystal molecules may be treated as the optical axis of the birefringent member.

Further, a transparent polymer film may be used as the birefringent member 40 (in this case, a uniaxially stretched one is preferable). In this case, the polymer film is PET
(Polyethylene terephthalate), acrylic resin, and polycarbonate are effective. Furthermore, in the above specific example, the single birefringent member was used.
In addition to the birefringent member 40, the lower electrode substrate 12 and the lower polarizing plate 1
6, another birefringent member can be inserted. In this case, Δn ₂ · d ₂ of these birefringent members may be readjusted.

[Specific Example 4] The basic structure is the same as that of "Specific Example 2". However, as shown in FIG.
Red, green, and blue color filters 33R, 33G, 33
B. Multi-color display is possible by providing the light shielding film 33D between the filters. FIG. 7 shows the relationship between the arrangement direction of the liquid crystal molecules, the twist direction of the liquid crystal molecules, the direction of the polarizing plate axis, and the optical axis of the birefringent member in "Specific Example 4".

In FIG. 9, a smooth layer 23 made of an insulator is formed on each of the color filters 33R, 33G, 33B and the light shielding film 33D to reduce the influence of these irregularities. An upper electrode 31 and an alignment film 21 are formed.

FIG. 10 shows a block diagram in which the liquid crystal display module 63 according to the present invention shown in FIG. 1 is used for a display section of a laptop personal computer, and FIG.

In FIG. 10, the microprocessor 49
The liquid crystal display module is driven by the driving IC 34 via the control LSI 48 based on the result calculated in the above. According to the present embodiment configured as described above, it is possible to provide a liquid crystal display device in which the overall thickness and weight of the liquid crystal display device can be reduced without lowering the rigidity and the display is not uneven due to the heat generated by the backlight light source. can do.

The invention described in the claims of the present invention is not limited to the above-mentioned STN type liquid crystal display device, but can be similarly applied to another type of liquid crystal display device equipped with a backlight. It is.

[0056]

As described above, according to the present invention,
The upper frame of the liquid crystal display is formed of a stainless steel sheet,
By forming the lower frame to be connected to the upper frame with a thin aluminum plate, it is possible to reduce the thickness of the intermediate frame without reducing the overall rigidity, to achieve a thinner and lighter body, and to achieve a direction perpendicular to the backlight light source. A cutout portion provided at a position symmetrical to a line orthogonal to the center of the backlight light source over at least the area of the liquid crystal display panel, a cutout portion provided immediately below the backlight light source in the longitudinal direction of the backlight, and the backlight. The notch provided at the lower part of both ends of the light source improves the heat radiation effect and forms a uniform temperature distribution on the entire surface of the liquid crystal display panel,
It is possible to provide various liquid crystal display devices capable of preventing display unevenness and obtaining a high-quality image display.

[Brief description of the drawings]

FIG. 1 is an exploded perspective view illustrating the configuration of an embodiment of a liquid crystal display device according to the present invention.

FIG. 2 is a plan view of a lower frame included in the liquid crystal display device according to the present invention.

FIG. 3 is an explanatory diagram showing the relationship among the alignment direction of liquid crystal molecules, the twist direction of liquid crystal molecules, the direction of the axis of a polarizing plate, and the optical axis of a birefringent member in the specific example 1 of the liquid crystal display device according to the present invention.

FIG. 4 is a perspective view of an essential part for explaining a stacking relation of components of the liquid crystal display device according to the present invention.

FIG. 5 is an explanatory diagram of the relationship among the alignment direction of liquid crystal molecules, the twist direction of liquid crystal molecules, the direction of the axis of a polarizing plate, and the optical axis of a birefringent member in a specific example 2 of the liquid crystal display device according to the present invention.

FIG. 6 is an explanatory diagram of contrast and transmitted light color-intersection angle α characteristics in the specific example 1 of the liquid crystal display device according to the present invention.

FIG. 7 is an explanatory diagram showing the relationship among the arrangement direction of liquid crystal molecules, the twist direction of liquid crystal molecules, the direction of the axis of a polarizing plate, and the optical axis of a birefringent member in Example 3 of the liquid crystal display device according to the present invention.

FIG. 8 shows an angle of intersection α,
FIG. 4 is an explanatory diagram of how to measure β and γ.

FIG. 9 is a partially cutaway perspective view illustrating the configuration of an upper electrode substrate in the liquid crystal display device according to the present invention.

FIG. 10 is a block diagram in a case where the liquid crystal display device according to the present invention is used for a display unit of a laptop personal computer.

FIG. 11 is an external view of a case where the liquid crystal display device according to the present invention is used for a display unit of a laptop personal computer.

[Explanation of symbols]

Reference Signs List 1 upper frame 2 lower frame 3 liquid crystal display window 13 spacer 14 adhesive tape fixing upper frame and liquid crystal display panel 17 lamp cover 18 cut-and-raised piece soldered to ground pad formed on drive circuit board 20 formed on lower frame Claw fixed to the claw receiver 35 Drive circuit board 36 Backlight light source (lamp) composed of a cold cathode tube 37 Light guide assembly composed of a light diffusion plate and a light guide plate 42 Intermediate frame 53 on which linear backlight is mounted 53, 54 Back Cutouts 55, 56 provided below lower ends of both ends of the light Cutouts 57, 58 provided at positions symmetrical to a line perpendicular to the center of the backlight 57, 58 Cutouts provided in the longitudinal direction of the backlight 62 Liquid crystal display panel .

──────────────────────────────────────────────────の Continued on the front page (72) Inventor Shigeharu Hatayama 3300 Hayano, Mobara City, Chiba Prefecture Inside the Electronic Devices Division, Hitachi, Ltd. (72) Inventor Toshimitsu Matsudo 3300 Hayano, Mobara City, Chiba Prefecture Hitachi, Ltd. (72) Inventor Takayuki Iura 3300 Hayano, Mobara City, Chiba Pref. Electronic Device Division, Hitachi, Ltd. (56) References JP-A-5-64044 (JP, A) JP-A-5-66390 (JP, A) JP-A-5-72514 (JP, A) JP-A-5-341285 (JP, A) JP-A-64-10780 (JP, U) (58) Fields investigated (Int. Cl. ⁶ , DB name) G02F 1/1335 530 F21V 8/00 601 G02F 1/1333

Claims (14)

(57) [Claims] 1. A liquid crystal display device for suppressing display unevenness, comprising: a metallic upper frame having a display window; and a liquid crystal display element disposed below the upper frame, the liquid crystal display element and a periphery of the liquid crystal display element. A liquid crystal display panel comprising a liquid crystal display element driving circuit substrate formed integrally with a liquid crystal display element; An intermediate frame disposed under the light guide assembly, accommodating the light guide assembly, and having a space for mounting a linear backlight light source on at least one side; A lower metal frame for fixing each member disposed between the upper frame and the upper frame by being connected to the upper frame; Longitudinal direction of The liquid crystal display device, characterized in that it is composed of a lower frame having a cut-out portion having a predetermined shape along. 2. The cut-out portion is provided so that the area of the lower frame formed immediately below the backlight light source is 10% to 50% of the area occupied by the backlight light source. The liquid crystal display device according to claim 1, wherein 3. The cut-out portion is provided so that the area of the lower frame formed immediately below the backlight light source is approximately 30% of the area occupied by the backlight light source. The liquid crystal display device according to claim 1. 4. The liquid crystal display device according to claim 1, wherein said upper frame is made of stainless steel, and said lower frame is made of aluminum. 5. A liquid crystal display device for suppressing display unevenness, comprising: a metallic upper frame having a display window; and a liquid crystal display element disposed below the upper frame, the liquid crystal display element and a periphery of the liquid crystal display element. A liquid crystal display panel comprising a liquid crystal display element driving circuit board formed integrally with a liquid crystal display element, and a light guide assembly disposed below the liquid crystal display panel and laminated with a light diffusion plate and a light guide plate An intermediate frame disposed below the light guide assembly, accommodating the light guide assembly, and having a space for mounting a linear backlight light source on at least one side; A metallic lower frame for fixing each member disposed between the upper frame and the lower frame by being connected to the upper frame, the lower frame being located immediately below the backlight light source. Light source The liquid crystal display device, characterized in that it is composed of a lower frame having a notch portion provided at positions corresponding to both end portions of the cutout portion of a predetermined shape along the longitudinal direction and the backlight source. 6. The cutout and the notch so that the area of the lower frame formed immediately below the backlight light source is 10% to 50% of the area occupied by the backlight light source. 6. The liquid crystal display device according to claim 5, further comprising: 7. The cutout and the cutout are provided so that the area of the lower frame formed immediately below the backlight light source is approximately 30% of the area occupied by the backlight light source. The liquid crystal display device according to claim 5, wherein: 8. The liquid crystal display device according to claim 5, wherein said upper frame is made of stainless steel, and said lower frame is made of aluminum. 9. A liquid crystal display device for suppressing display unevenness, comprising a metallic upper frame having a display window, a liquid crystal display element disposed below the upper frame, and a periphery of the liquid crystal display element. A liquid crystal display panel comprising a liquid crystal display element driving circuit board formed integrally with a liquid crystal display element, and a light guide assembly disposed below the liquid crystal display panel and laminated with a light diffusion plate and a light guide plate An intermediate frame disposed below the light guide assembly, accommodating the light guide assembly, and having a space for mounting a linear backlight light source on at least one side; A metallic lower frame for fixing each member disposed between the upper frame and the lower frame by being connected to the upper frame, the lower frame being located immediately below the backlight light source. Light source A first cutout having a predetermined shape along the hand direction, a cutout provided at a position corresponding to both ends of the backlight light source, and a center portion of the backlight light source over a region corresponding to the liquid crystal display panel. And a lower frame having a second cutout portion of a predetermined shape provided at a position symmetrical to a line passing through the backlight light source and orthogonal to the longitudinal direction of the backlight light source. 10. The first frame so that the area of the lower frame formed immediately below the backlight light source is 10% to 50% of the area occupied by the backlight light source.
10. The liquid crystal display device according to claim 9, wherein the cutout portion and the cutout portion are provided. 11. The first cutout and the notch so that the area of the lower frame formed immediately below the backlight light source is approximately 30% of the area occupied by the backlight light source. 10. The liquid crystal display device according to claim 9, further comprising: 12. The second cutout portion is provided so that the area of the lower frame formed below the liquid crystal display panel is 10% to 50% of the area occupied by the liquid crystal display panel. 10. The liquid crystal display device according to claim 9, wherein: 13. The method according to claim 12, wherein the second cutout is provided so that an area of the lower frame formed below the liquid crystal display panel is approximately 30% of an area occupied by the liquid crystal display panel. 10. The liquid crystal display device according to claim 9, wherein: 14. The upper frame is made of stainless steel,
14. The liquid crystal display device according to claim 9, wherein the lower frame is made of aluminum.